Japanese Unexamined Utility Model Publication Nos. 81031 (1980) and 146147 (1986), and Japanese Examined Utility Model Publication No. 23150 (1982) proposed the use of photoreflective sheets to use sunlight more effectively for the growth of vegetables and fruits, and the coloration of fruits. Such a sheet was made of a base cloth covered with a metal foil (aluminum foil) for photo diffused reflection. The cloth was woven of a tape-type yarn like a slit yarn.
Other kinds of sheets using a photoreflective material such as a metal foil or a metal deposition film are known; for example, a reflective thermal sheet as proposed by Japanese Unexamined Utility Model Publication No. 174036 (1982). The reflective thermal sheet reported was made of a soft, synthetic resin film having a metal deposition layer on its face and a foam laminated on the film. Further, the use of a cushioned base material like an air mattress is proposed by Japanese Unexamined Utility Model Publication No. 103837 (1982).
Conventional photoreflective sheets were, however, less cushioned so that the sheets often damaged fruit, leaves, branches, etc. due to strong winds. Unexpectedly strong winds cause fruit to drop, resulting in a considerable deterioration of the commercial value of produce. A cushioned base like an air mattress made the sheet too expensive for large-scale agricultural use. In addition, such a cushion-type sheet was difficult to repair, lay out; or put away into storage. Conventional photoreflective sheets were merely intended to reflect sunlight onto fruits, and not to protect plants from pests such as animals, birds, insects, fungi, herbs or the like.
The invention provides a photoreflective sheet which is soft, light, appropriately cushioned and superior in photo diffused reflection.
The invention also provides a photoreflective sheet which reflects sunlight suitably to plants, and which contains a certain chemical preparation to protect the plants from pests.